The childhood obesity epidemic has led to the rising prevalence of cardiometabolic risks in adolescents. These risks include abdominal obesity, hypertension, dyslipidemia and pre-diabetes, the clustering of which is known as metabolic (or insulin resistance) syndrome. Longitudinal data show that children and adolescents with metabolic syndrome are more likely to develop cardiovascular disease and type-2 diabetes. This is especially worrisome for youth in New Mexico, a culturally diverse state with 44.9% Hispanics and 9.7% American Indians, because obesity disproportionately affects these populations. School-based health centers (SBHCs) offer an important venue to expand healthcare access for adolescents, who are traditionally hard-to- reach. SBHCs provide health services to all students, with a focus on the uninsured and underserved and may be the only point of intervention for low-income and minority youth. The proposed R01 study will build upon significant findings from a NIH/NHLBI funded R21 study that utilized a community-based participatory research approach to develop and pilot-test a SBHC weight management program called Adolescents Committed to Improvement of Nutrition and Physical Activity (ACTION) with two high schools. ACTION was based on the use of motivational interviewing (MI) to support adoption of healthier eating and physical activity behaviors. In this current proposal (ACTION PAC), we propose to collaborate with eight high schools that have SBHCs to evaluate the broader reach and efficacy of using MI-based approaches to prevent and treat overweight/obesity and to decrease the risk of metabolic syndrome development. Specifically, our goals are to 1) prevent the development of overweight and obesity among students with BMI <85th percentile, 2) reduce BMI z score and insulin resistance in students with BMI >=85th percentile, and 3) obtain student and parent feedback on their experience with school-based BMI screening and weight management. To test the efficacy of these MI-based approaches, we will employ a cluster randomized control trial design in which four of the eight high schools will be randomized to an intervention group and the other four high schools will be randomized to a usual care comparison group. 960 participants in the 9th and 10th grades between the ages of 14-17 years will be followed annually for two years (until their 11th and 12th grade, respectively). Analyses will be conducted in a multilevel framework to account for clustering within schools. Baseline and 2nd year comparisons within group and comparison of change between the intervention and comparison groups will be assessed. The collective impact of these research outcomes will advance the field of school-based obesity intervention studies and take a significant step towards identifying sustainable prevention and treatment approaches for adolescent obesity and metabolic syndrome through the use of SBHCs.